A Mutation in fat2 Uncouples Tissue Elongation from Global Tissue Rotation

• The intracellular region of Fat2 is dispensable for alignment of collagen IV fibers
• The intracellular region of Fat2 is dispensable for egg chamber elongation
• The intracellular region of Fat2 is essential for egg chamber rotation
• Egg chamber elongation can be uncoupled from egg chamber rotation

SummaryGlobal tissue rotation was proposed as a morphogenetic mechanism controlling tissue elongation. In Drosophila ovaries, global tissue rotation of egg chambers coincides with egg chamber elongation. Egg chamber rotation was put forward to result in circumferential alignment of extracellular fibers. These fibers serve as molecular corsets to restrain growth of egg chambers perpendicular to the anteroposterior axis, thereby leading to the preferential egg chamber elongation along this axis. The atypical cadherin Fat2 is required for egg chamber elongation, rotation, and the circumferential alignment of extracellular fibers. Here, we have generated a truncated form of Fat2 that lacks the entire intracellular region. fat2 mutant egg chambers expressing this truncated protein fail to rotate yet display normal extracellular fiber alignment and properly elongate. Our data suggest that global tissue rotation, even though coinciding with tissue elongation, is not a necessary prerequisite for elongation.

Graphical AbstractFigure optionsDownload as PowerPoint slide